1) Some truths can hurt society Topics like unfriendly artificial intelligence make me question the assumption that I always want intellectual progress in all areas. If we as modern society were to choose any topic which restricting thought about might be very useful, UFAI seems like a good choice. Maybe the freedom of thought in this issue might be a necessary casualty to avoid a much worse conclusion.

I'm not sure why freedom of thought is in principle a bad thing in this case. I can think about whatever horrible thing I want, but unless I act upon my thoughts, I see no danger in it. I'm pretty sure that some people get off with rape fantasies, or seriously considers murdering someone, but if they don't act upon their thoughts I see no problem with it. Then of course thinking usually does have consequences: depressed people are often encouraged not to daydream and focus on concrete tasks, for example. But this kind of distinction is true in many kind of situations: while in principle having the fridge stocked with wine wouldn't hurt a former alcoholic, in practice it's much better if they stay as far away as possible from temptation.